1. Field of the Invention
The present invention relates generally to video camera apparatus and, more particularly, is directed to a video camera having a camera body with an imager for producing a video signal and exchangeable lens devices selectively mounted on the body.
2. Description of the Prior Art
In a widely used optical still camera according to the prior art, a plurality of exchangeable lens devices with different optical characteristics are provided for selective mounting on a camera body.
Similarly, it has been proposed, for example, in U.S. patent application Ser. No. 07/301,597, filed Jan. 26, 1989, and having a common assignee herewith, to provide a video camera apparatus with a camera body containing an imager for producing a video signal corresponding to an image projected thereon, and a plurality of exchangeable lens devices selectively mounted on the camera body and having respective different optical characteristics for adopting the video camera apparatus to various conditions.
Generally, in a video camera apparatus, a real moving picture is picked up by the imager which may include a charge coupled device (CCD) or the like, and the picture is converted to an electrical signal which constitutes the output video signal. The exchangeable lens devices with different optical characteristics which are selectively mounted on the camera body include, for example, a telephoto-lens device, a wide-angle lens device, a zoom lens device and so on, each of which has a different focal length. When the cameraman selects one of the lens devices and mounts the same on the camera body for use therewith, components in the camera body have to control the selected lens device, for example, to effect automatic focus control, automatic exposure control, automatic white/black balance control and the like. In such case, control modes are different depending on the optical characteristics of the lens devices, for example, the focal length, F number, spectrum characteristics and the like. Further, the optical characteristics that need to be controlled are different for different kinds of lens devices.